Electropolish assisted electrochemical mechanical polishing apparatus

ABSTRACT

Methods and apparatus are provided for processing a substrate in an electrochemical mechanical planarizing system. An apparatus is provided for processing a substrate including a planarizing module, at least one electrochemical mechanical polishing station disposed on the planarizing module, at least one polishing head disposed above the planarizing module and the at least one polishing head adapted to selectively lower a substrate retained in the polishing head to the electrochemical mechanical polishing station, a factory interface disposed adjacent both the planarizing module, a loading robot disposed between the factory interface and the planarizing module, and an electrochemical polishing station disposed on or adjacent the planarizing module, the factory interface, or a combination thereof. The electrochemical polishing station may be disposed on the planarizing module, adjacent the planarizing module, in the factory interface, adjacent the factory interface, or between the planarizing module and the factory interface.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. provisional patent applicationSer. No. 60/785,323, filed Mar. 23, 2006, which is herein incorporatedby reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the present invention generally relate to a method andapparatus for electrochemical processing of a substrate.

2. Description of the Related Art

Electrochemical mechanical planarizing (Ecmp) is a technique used toremove conductive materials from a substrate surface by electrochemicaldissolution while concurrently polishing the substrate with reducedmechanical abrasion compared to conventional planarization processes.Ecmp systems may generally be adapted for deposition of conductivematerial on the substrate by reversing the polarity of the bias.Electrochemical dissolution is performed by applying a bias between asecond electrode and a substrate surface to remove conductive materialsfrom the substrate surface into a surrounding electrolyte. Typically,the bias is applied to the substrate surface by a conductive polishingmaterial on which the substrate is processed. A mechanical component ofthe polishing process is performed by providing relative motion betweenthe substrate and the conductive polishing material that enhances theremoval of the conductive material from the substrate.

In many conventional systems, Ecmp of the conductive film is followed byconventional chemical mechanical processing for barrier removal. Thisdichotomy of processing (e.g., Ecmp and CMP on a single system) requiresdivergent utilities and process consumables, resulting in higher cost ofownership. Moreover, as most Ecmp processes utilize lower contactpressure between the substrate being processed and a processing surface,the heads utilized to retain the substrate during processing do notprovide robust processing performance when utilized for conventional CMPprocesses, which typically have high contact pressures, which results inhigh erosion of conductive material disposed in trenches or otherfeatures. As the removal rate of low pressure conventional CMP barrierlayer processing is generally less than about 100 Å/min, conventionalCMP processing of barrier materials using low pressure is not suitablefor large scale commercialization. Thus, it would be advantageous for asystem to be enabled to remove barrier materials, such as ruthenium,tantalum, tantalum nitride, titanium, titanium nitride and the like,through an electrochemical process.

Thus, there is a need for an improved method and apparatus forelectrochemical processing of metal and barrier materials.

SUMMARY OF THE INVENTION

Embodiments of the invention as recited in the claims generally providean apparatus for processing a substrate in an electrochemical mechanicalplanarizing system. In certain embodiments, an apparatus is provided forprocessing a substrate including a planarizing module, at least oneelectrochemical mechanical polishing station disposed on the planarizingmodule, at least one polishing head disposed above the planarizingmodule and the at least one polishing head adapted to selectively lowera substrate retained in the polishing head to the electrochemicalmechanical polishing station, a factory interface disposed adjacent theplanarizing module, a loading robot disposed adjacent both the factoryinterface and the planarizing module, and an electrochemical polishingstation disposed on or adjacent the planarizing module, the factoryinterface, or a combination thereof. The electrochemical polishingstation may be disposed on the planarizing module, adjacent theplanarizing module, in the factory interface, adjacent the factoryinterface, or between the planarizing module and the factory interface.

In certain embodiments, a method of polishing a substrate comprisingfeature definitions formed in a dielectric material, a barrier layerdeposited conformally over the dielectric layer and in the featuredefinitions, and a conductive layer disposed on the barrier layer tofill the feature definitions is provided. A system comprising a factoryinterface, an electrochemical polishing station, and a planarizingmodule containing three electrochemical mechanical polishing stations isprovided. A substrate is introduced to the electrochemical polishingstation configured to remove conductive material from a substrate in amechanical free polishing process by the application of a bias in thepresence of a conductive polishing solution to remove conductivematerial by anodic dissolution. A bulk portion of the conductive layeris removed from the substrate. The substrate is transferred to the firstelectrochemical mechanical polishing station. The substrate is polishedto remove a bulk portion of the conductive layer from the substrate. Thesubstrate is transferred to the second electrochemical mechanicalpolishing station. Any remaining conductive material is removed from thesubstrate to expose the barrier layer. The substrate is transferred tothe third electrochemical mechanical polishing station and the barrierlayer is removed from the substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited embodiments of theinvention are attained and can be understood in detail, a moreparticular description of the invention, briefly summarized above, maybe had by reference to the embodiments thereof which are illustrated inthe appended drawings. It is to be noted, however, that the appendeddrawings illustrate only typical embodiments of this invention and aretherefore not to be considered limiting of its scope, for the inventionmay admit to other equally effective embodiments.

FIG. 1A is a plan view of one embodiment of an electrochemicalmechanical planarizing system;

FIG. 1B is a plan view of another embodiment of an electrochemicalmechanical planarizing system;

FIG. 2 is a sectional view of one embodiment of a first electrochemicalmechanical planarizing (Ecmp) station of the system of FIG. 1;

FIG. 3A is a partial sectional view of the bulk Ecmp station through twocontact assemblies;

FIGS. 3B-C are sectional views of alternative embodiments of contactassemblies;

FIGS. 3D-E are sectional views of plugs;

FIGS. 4A-B are side, exploded and sectional views of one embodiment of acontact assembly;

FIG. 5 is one embodiment of a contact element;

FIG. 6 is a perspective view of another embodiment of another Ecmpstation;

FIG. 7 illustrates a partial sectional perspective view of an exemplaryelectrochemical polishing cell of the invention.

FIG. 8 illustrates a perspective view of a first electrode/secondelectrode base plate of the invention.

FIG. 9 illustrates a perspective view of an exemplary firstelectrode/second electrode base plate of the invention having a firstelectrode positioned therein.

FIG. 10 illustrates an exploded perspective view of an exemplarymembrane support member of the invention.

FIG. 11 illustrates a partial sectional view of an edge of the polishingcell of the invention.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements and/or process steps ofone or more embodiments may be beneficially incorporated in one or moreother embodiments without additional recitation.

DETAILED DESCRIPTION

Embodiments for a system and method for removal of conductive andbarrier materials from a substrate are provided. Although theembodiments disclosed below focus primarily on removing material from,e.g., planarizing, a substrate, it is contemplated that the teachingsdisclosed herein may be used to electroplate a substrate by reversingthe polarity of an electrical bias applied between the substrate and anelectrode of the system.

FIG. 1A is a plan view of one embodiment of a planarization system 100having an apparatus for electrochemically processing a substrate. Theexemplary system 100 generally comprises a factory interface 102, aloading robot 104, and a planarizing module 106. The loading robot 104is disposed proximate the factory interface 102 and the planarizingmodule 106 to facilitate the transfer of substrates 122 therebetween.

A controller 108 is provided to facilitate control and integration ofthe modules of the system 100. The controller 108 comprises a centralprocessing unit (CPU) 110, a memory 112, and support circuits 114. Thecontroller 108 is coupled to the various components of the system 100 tofacilitate control of, for example, the planarizing, cleaning, andtransfer processes.

The factory interface 102 generally includes a cleaning module 116 andone or more wafer cassettes 118. An interface robot 120 is employed totransfer substrates 122 between the wafer cassettes 118, the cleaningmodule 116 and an input module 124. The input module 124 is positionedto facilitate transfer of substrates 122 between the planarizing module106 and the factory interface 102 by grippers, for example vacuumgrippers or mechanical clamps.

The planarizing module 106 includes at least a first electrochemicalmechanical planarizing (Ecmp) station 128, disposed in anenvironmentally controlled enclosure 188. Examples of planarizingmodules 106 that can be adapted to benefit from the invention includeMIRRA®, MIRRA MESA™, REFLEXION®, REFLEXION® LK, and REFLEXION LK Ecmp™Chemical Mechanical Planarizing Systems, all available from AppliedMaterials, Inc. of Santa Clara, Calif. Other planarizing modules,including those that use processing pads, planarizing webs, or acombination thereof, and those that move a substrate relative to aplanarizing surface in a rotational, linear or other planar motion mayalso be adapted to benefit from the invention.

In the embodiment depicted in FIG. 1, the planarizing module 106includes the first Ecmp station 128, a second Ecmp station 130, and athird Ecmp station 132. Bulk removal of conductive material disposed onthe substrate 122 may be performed through an electrochemicaldissolution process at the first Ecmp station 128. After the bulkmaterial removal at the first Ecmp station 128, the remaining conductivematerial is removed from the substrate at the second Ecmp station 130through a multi-step electrochemical mechanical process, wherein part ofthe multi-step process is configured to remove residual conductivematerial. It is contemplated that more than one Ecmp station may beutilized to perform the multi-step removal process after the bulkremoval process performed at a different station. Alternatively, each ofthe first and second Ecmp stations 128, 130 may be utilized to performboth the bulk and multi-step conductive material removal on a singlestation. It is also contemplated that all Ecmp stations (for example 3stations of the module 106 depicted in FIG. 1) may be configured toprocess the conductive layer with a two step removal process.

Alternatively, a chemical mechanical polishing (CMP) station may besubstituted for one or more of the Ecmp stations 128, 130, and 132. Itis contemplated that other CMP processes may be alternatively performed.As the CMP stations 132 are conventional in nature, further descriptionthereof has been omitted for the sake of brevity.

The exemplary planarizing module 106 also includes a transfer station136 and a carousel 134 that are disposed on an upper or first side 138of a machine base 140. In one embodiment, the transfer station 136includes an input buffer station 142, an output buffer station 144, atransfer robot 146, and a load cup assembly 148. The input bufferstation 142 receives substrates from the factory interface 102 by meansof the loading robot 104. The loading robot 104 is also utilized toreturn polished substrates from the output buffer station 144 to thefactory interface 102. The transfer robot 146 is utilized to movesubstrates between the buffer stations 142, 144 and the load cupassembly 148.

In certain embodiments, the transfer robot 146 includes two gripperassemblies, each having pneumatic gripper fingers that hold thesubstrate by the substrate's edge. The transfer robot 146 maysimultaneously transfer a substrate to be processed from the inputbuffer station 142 to the load cup assembly 148 while transferring aprocessed substrate from the load cup assembly 148 to the output bufferstation 144. An example of a transfer station that may be used toadvantage is described in U.S. Pat. No. 6,156,124, entitled WAFERTRANSFER STATION FOR A CHEMICAL MECHANICAL POLISHER, issued Dec. 5, 2000to Tobin, which is herein incorporated by reference in its entirety.

The carousel 134 is centrally disposed on the base 140. The carousel 134typically includes a plurality of arms 150, each supporting aplanarizing head assembly 152. Two of the arms 150 depicted in FIG. 1are shown in phantom such that the transfer station 136 and aplanarizing surface 126 of the first Ecmp station 128 may be seen. Thecarousel 134 is indexable such that the planarizing head assemblies 152may be moved between the planarizing stations 128, 130, 132 and thetransfer station 136. One carousel that may be utilized to advantage isdescribed in U.S. Pat. No. 5,804,507, issued Sep. 8, 1998 to Perlov, etal., which is hereby incorporated by reference in its entirety.

A conditioning device 182 is disposed on the base 140 adjacent each ofthe planarizing stations 128, 130, 132. The conditioning device 182periodically conditions the planarizing material disposed in thestations 128, 130, 132 to maintain uniform planarizing results.

An electropolishing cell 700 as described herein as follows and in FIGS.7-11 may be disposed on the system 100. The electropolishing cell 700allows for removal of conductive material from the substrate in amechanical free polishing process by the application of bias in thepresence of a conductive electrolyte solution to remove conductivematerial by anodic dissolution. An example of a suitable cell forelectropolishing is the SlimCell ECP™ commercially available fromApplied Materials, of Santa Clara, Calif.

The electropolishing cell may be position in several areas of the system100 as noted as 190A, 190B, 190C, 190D, 190E, 190F, and 190G, amongothers. In other embodiments of the system 100, multipleelectropolishing cells may be used and positioned in various placesaround the system 100. Preferably, the electropolishing cell is disposedadjacent both a cleaning station/load cup and a robot for substratetransfer. The electropolishing cell 700 is generally attached to thesystem 100 to provide for efficient processing of the substrate withinthe system 100 without breaking the clean environment of the system.

The electropolishing cell 190A may be positioned adjacent the wafercassettes 118 and interface robot 120 of the factory interface 102. Theelectropolishing cell 190B may be positioned adjacent the cleaningmodule 116 of the factory interface 102. Alternatively, theelectropolishing cell 190C may be positioned within the cleaning module116 as shown with broken lines. In such a position in or adjacent thecleaning module 116, the electropolishing of the substrate may beperformed in conjunction with cleaning of the substrate before transferto the planarizing module 106. In an alternative position of theelectropolishing cell 700 in the system 100, the electropolishing cell190D may be positioned on the planarizing module 106. In such anembodiment, the electropolishing cell 700 may be disposed adjacent thetransfer station 136 and an Ecmp station, such as Ecmp station 132, asshown in FIG. 1, or Ecmp station 128. Alternatively, theelectropolishing cell 190D may be positioned between two Ecmp stations,for example, between the second Ecmp station 130 and the third Ecmpstation 132 or between the frist Ecmp staion 128 and the second Ecmpstation 130.

FIG. 1B is a plan view of another embodiment of a planarization system200 having an apparatus for electrochemically processing a substrate.The exemplary system 200 generally comprises a factory interface 192, aloading robot 194, and a planarizing module 196. The cleaning module 116of the factory interface 192 has the cleaning module 116 positioned inparallel with the loading robot 194 rather than the perpendicularposition of the cleaning module 116 in the system 100 of FIG. 1A. Thefactory interface comprises an input module disposed adjacent thecassettes 118, and a cleaning module 116 disposed adjacent the inputmodule. The loading robot 194 is positioned within the factory interface192 on a running beam 195 to allow movement between the interface robot120, the cleaning module 116, and the planarizing module 196 as well asanother other devices or processing cells disposed in the factoryinterface 192 to facilitate the transfer of substrates 122 therebetween.

The electropolishing cell 700 of the system 200 may be positionedadjacent the wafer cassettes 118 as shown as polishing cell 190Fadjacent the interface robot 120 of the factory interface 102. Theelectropolishing cell 190E may be positioned adjacent the cleaningmodule 116 of the factory interface 102. Alternatively, theelectropolishing cell 190E may be positioned on the cleaning module 116or in a stack with another device in the factory interface. In analternative position of the electropolishing cell 700 in the system 200,the electropolishing cell 190G may be positioned on the planarizingmodule 196. In such an embodiment, the electropolishing cell 190G may bedisposed in the position of the transfer station 136 or adjacent anytransfer station, such as transfer station 136 shown in FIG. 1A disposedon the system 200. Additionally, electropolishing cell 190G may bepositioned between any transfer station and an Ecmp station, such asEcmp station 132 shown in FIG. 1B or Ecmp station 128. Alternatively,the electropolishing cell 190G may be positioned between two Ecmpstations.

FIG. 2 depicts a sectional view of one of the planarizing headassemblies 152 positioned over one embodiment of the first Ecmp station128. The second and third Ecmp stations 130, 132 may be similarlyconfigured. The planarizing head assembly 152 generally comprises adrive system 202 coupled to a planarizing head 204. The drive system 202generally provides at least rotational motion to the planarizing head204. The planarizing head 204 additionally may be actuated toward thefirst Ecmp station 128 such that the substrate 122 retained in theplanarizing head 204 may be disposed against the planarizing surface 126of the first Ecmp station 128 during processing. The drive system 202 iscoupled to the controller 108 that provides a signal to the drive system202 for controlling the rotational speed and direction of theplanarizing head 204.

In certain embodiments, the planarizing head may be a TITAN HEAD™ orTITAN PROFILER™ wafer carrier manufactured by Applied Materials, Inc.Generally, the planarizing head 204 comprises a housing 214 andretaining ring 224 that defines a center recess in which the substrate122 is retained. The retaining ring 224 circumscribes the substrate 122disposed within the planarizing head 204 to prevent the substrate fromslipping out from under the planarizing head 204 while processing. Theretaining ring 224 can be made of plastic materials such as PPS, PEEK,and the like, or conductive materials such as stainless steel, Cu, Au,Pd, and the like, or some combination thereof. It is furthercontemplated that a conductive retaining ring 224 may be electricallybiased to control the electric field during Ecmp. Conductive or biasedretaining rings tend to slow the polishing rate proximate the edge ofthe substrate. It is contemplated that other planarizing heads may beutilized.

The first Ecmp station 128 generally includes a platen assembly 230 thatis rotationally disposed on the base 140. The platen assembly 230 issupported above the base 140 by a bearing 238 so that the platenassembly 230 may be rotated relative to the base 140. An area of thebase 140 circumscribed by the bearing 238 is open and provides a conduitfor the electrical, mechanical, pneumatic, control signals andconnections communicating with the platen assembly 230.

Conventional bearings, rotary unions and slip rings, collectivelyreferred to as rotary coupler 276, are provided such that electrical,mechanical, fluid, pneumatic, control signals and connections may becoupled between the base 140 and the rotating platen assembly 230. Theplaten assembly 230 is typically coupled to a motor 232 that providesthe rotational motion to the platen assembly 230. The motor 232 iscoupled to the controller 108 that provides a signal for controlling forthe rotational speed and direction of the platen assembly 230.

A top surface 260 of the platen assembly 230 supports a processing padassembly 222 thereon. The processing pad assembly may be coupled withthe platen assembly 230 by magnetic attraction, vacuum, clamps,adhesives and the like.

A plenum 206 is defined in the platen assembly 230 to facilitate uniformdistribution of electrolyte to the planarizing surface 126. A pluralityof passages, described in greater detail below, are formed in the platenassembly 230 to allow electrolyte, provided to the plenum 206 from anelectrolyte source 248, to flow uniformly though the platen assembly 230and into contact with the substrate 122 during processing. It iscontemplated that different electrolyte compositions may be providedduring different stages of processing or at different Ecmp stations 128,130, 132.

The processing pad assembly 222 includes an electrode 292 and at least aplanarizing portion 290. The electrode 292 comprises a conductivematerial, such as stainless steel, copper, aluminum, gold, silver andtungsten, among others. The electrode 292 may be solid, impermeable toelectrolyte, permeable to electrolyte or perforated. At least onecontact assembly 250 extends above the processing pad assembly 222 andis adapted to electrically couple the substrate being processing on theprocessing pad assembly 222 to the power source 242. The electrode 292is also coupled to the power source 242 so that an electrical potentialmay be established between the substrate and electrode 292.

A meter 244 is provided to detect a metric indicative of theelectrochemical process. The meter 244 may be coupled or positionedbetween the power source 242 and at least one of the electrode 292 orcontact assembly 250. The meter 244 may also be integral to the powersource 242. In one embodiment, the meter 244 is configured to providethe controller 108 with a metric indicative of processing, such as acharge, current and/or voltage. This metric may be utilized by thecontroller 108 to adjust the processing parameters in-situ or tofacilitate endpoint or other process stage detection.

A window 246 is provided through the pad assembly 222 and/or platenassembly 230, and is configured to allow a sensor 254, positioned belowthe pad assembly 222, to sense a metric indicative of polishingperformance. For example, the sensor 254 may be an eddy current sensoror an interferometer, among other sensors. The metric, provided by thesensor 254 to the controller 108, provides information that may beutilized for processing profile adjustment in-situ, endpoint detectionor detection of another point in the electrochemical process. In oneembodiment, the sensor 254 an interferometer capable of generating acollimated light beam, which during processing, is directed at andimpinges on a side of the substrate 122 that is being polished. Theinterference between reflected signals is indicative of the thickness ofthe conductive layer of material being processed. One sensor that may beutilized to advantage is described in U.S. Pat. No. 5,893,796, entitledFORMING A TRANSPARENT WINDOW IN A POLISHING PAD FOR A CHEMICALMECHANICAL POLISHING APPARATUS, issued Apr. 13, 1999, to Birang, et al.,which is hereby incorporated by reference in its entirety.

Embodiments of the processing pad assembly 222 suitable for removal ofconductive material from the substrate 122 may generally include aplanarizing surface 126 that is substantially dielectric. Otherembodiments of the processing pad assembly 222 suitable for removal ofconductive material from the substrate 122 may generally include aplanarizing surface 126 that is substantially conductive. At least onecontact assembly 250 is provided to couple the substrate with the powersource 242 so that the substrate may be biased relative to the electrode292 during processing. Apertures 210, formed through the planarizingportion 290, allow the electrolyte to establish a conductive pathbetween the substrate 122 and electrode 292.

In one embodiment, the planarizing portion 290 of the processing padassembly 222 is a dielectric, such as polyurethane. Examples ofprocessing pad assemblies that may be adapted to benefit from theinvention are described in U.S. Pat. No. 6,991,528, entitled CONDUCTIVEPLANARIZING ARTICLE FOR ELECTROCHEMICAL MECHANICAL PLANARIZING, Jan. 31,2006, and U.S. patent application Ser. No. 10/455,895, filed Jun. 6,2003 by Y. Hu et al., entitled CONDUCTIVE PLANARIZING ARTICLE FORELECTROCHEMICAL MECHANICAL PLANARIZING, both of which are herebyincorporated by reference in their entireties.

FIG. 3A is a partial sectional view of the first Ecmp station 128through two contact assemblies 250, and FIGS. 4A-C are side, explodedand sectional views of one of the contact assemblies 250 shown in FIG.3A. The platen assembly 230 includes at least one contact assembly 250projecting therefrom and coupled to the power source 242 that is adaptedto bias a surface of the substrate 122 during processing. The contactassemblies 250 may be coupled to the platen assembly 230, part of theprocessing pad assembly 222, or a separate element. Although two contactassemblies 250 are shown in FIG. 3A, any number of contact assembliesmay be utilized and may be distributed in any number of configurationsrelative to the centerline of the platen assembly 230.

The contact assemblies 250 are generally electrically coupled with thepower source 242 through the platen assembly 230 and are movable toextend at least partially through respective apertures 368 formed in theprocessing pad assembly 222. The positions of the contact assemblies 250may be chosen to have a predetermined configuration across the platenassembly 230. For predefined processes, individual contact assemblies250 may be repositioned in different apertures 368, while apertures notcontaining contact assemblies may be plugged with a stopper 392 orfilled with a nozzle 394 (as shown in FIGS. 3D-E) that allows flow ofelectrolyte from the plenum 206 to the substrate. One contact assemblythat may be adapted to benefit from the invention is described in U.S.Pat. No. 6,854,153, entitled APPARATUS FOR ELECTROCHEMICAL PROCESSING,issued Apr. 26, 2005, and is hereby incorporated by reference in itsentirety.

Although the embodiments of the contact assembly 250 described belowwith respect to FIG. 3A depicts a rolling ball contact, the contactassembly 250 may alternatively comprise a structure or assembly having aconductive upper layer or surface suitable for electrically biasing thesubstrate 122 during processing. For example, as depicted in FIG. 3B,the contact assembly 250 may include a pad structure 350 having an upperlayer 352 made from a conductive material or a conductive composite(i.e., the conductive elements are dispersed integrally with or comprisethe material comprising the upper surface), such as a polymer matrix 354having conductive particles 356 dispersed therein or a conductive coatedfabric, among others. The pad structure 350 may include one or more ofthe apertures 210 formed therethrough for electrolyte delivery to theupper surface of the pad assembly. Other examples of suitable contactassemblies are described in U.S. patent application Ser. No. 10/880,752,filed Jun. 30, 2004, entitled METHOD AND APPARATUS FOR ELECTROCHEMICALMECHANICAL PROCESSING, which is hereby incorporated by reference in itsentirety.

In certain embodiments, each of the contact assemblies 250 includes ahollow housing 302, an adapter 304, a ball 306, a contact element 314and a clamp bushing 316. The ball 306 has a conductive outer surface andis movably disposed in the housing 302. The ball 306 may be disposed ina first position having at least a portion of the ball 306 extendingabove the planarizing surface 126 and at least a second position wherethe ball 306 is substantially flush with the planarizing surface 126. Itis also contemplated that the ball 306 may move completely below theplanarizing surface 126. The ball 306 is generally suitable forelectrically coupling the substrate 122 to the power source 242. It iscontemplated that a plurality of balls 306 for biasing the substrate maybe disposed in a single housing 358 as depicted in FIG. 3C.

The power source 242 generally provides a positive electrical bias tothe ball 306 during processing. Between planarizing substrates, thepower source 242 may optionally apply a negative bias to the ball 306 tominimize attack on the ball 306 by process chemistries.

The housing 302 is configured to provide a conduit for the flow ofelectrolyte from the source 248 to the substrate 122 during processing.The housing 302 is fabricated from a dielectric material compatible withprocess chemistries. A seat 326 formed in the housing 302 prevents theball 306 from passing out of the first end 308 of the housing 302. Theseat 326 optionally may include one or more grooves 348 formed thereinthat allow fluid flow to exit the housing 302 between the ball 306 andseat 326. Maintaining fluid flow past the ball 306 may minimize thepropensity of process chemistries to attack the ball 306.

The contact element 314 is coupled between the clamp bushing 316 and theadapter 304. The contact element 314 is generally configured toelectrically connect the adapter 304 and ball 306 substantially orcompletely through the range of ball positions within the housing 302.In certain embodiments, the contact element 314 may be configured as aspring form.

In the embodiment depicted in FIGS. 3 and 4A-C and detailed in FIG. 5,the contact element 314 includes an annular base 342 having a pluralityof flexures 344 extending therefrom in a polar array. The flexure 344 isgenerally fabricated from a resilient and conductive material suitablefor use with process chemistries. In certain embodiments, the flexure344 is fabricated from gold plated beryllium copper.

Returning to FIGS. 3A and 4A-B, the clamp bushing 316 includes a flaredhead 424 having a threaded post 426 extending therefrom. The clampbushing 316 may be fabricated from either a dielectric or conductivematerial, or a combination thereof, and in certain embodiments, isfabricated from the same material as the housing 302. The flared head424 maintains the flexures 344 at an acute angle relative to thecenterline of the contact assembly 250 so that the flexures 344 of thecontact elements 314 are positioned to spread around the surface of theball 306 to prevent bending, binding and/or damage to the flexures 344during assembly of the contact assembly 250 and through the range ofmotion of the ball 306.

The ball 306 may be solid or hollow and is typically fabricated from aconductive material. For example, the ball 306 may be fabricated from ametal, conductive polymer or a polymeric material filled with conductivematerial, such as metals, conductive carbon or graphite, among otherconductive materials. Alternatively, the ball 306 may be formed from asolid or hollow core that is coated with a conductive material. The coremay be non-conductive and at least partially coated with a conductivecovering.

The ball 306 is generally actuated toward the planarizing surface 126 byat least one of spring, buoyant or flow forces. In the embodimentdepicted in FIG. 3, flow through the passages formed through the adapter304 and clamp bushing 316 and the platen assembly 230 from theelectrolyte source 248 urge the ball 306 into contact with the substrateduring processing.

FIG. 6 is a sectional view of one embodiment of the second Ecmp station130. The first and third Ecmp stations 128, 132 may be configuredsimilarly. The second Ecmp station 130 generally includes a platen 602that supports a fully conductive processing pad assembly 604. The platen602 may be configured similar to the platen assembly 230 described aboveto deliver electrolyte through the processing pad assembly 604, or theplaten 602 may have a fluid delivery arm (not shown) disposed adjacentthereto configured to supply electrolyte to a planarizing surface of theprocessing pad assembly 604. The platen assembly 602 includes at leastone of a meter 244 or sensor 254 (shown in FIG. 2) to facilitateendpoint detection.

In one embodiment, the processing pad assembly 604 includes interposedpad 612 sandwiched between a conductive pad 610 and an electrode 614.The conductive pad 610 is substantially conductive across its topprocessing surface and is generally made from a conductive material or aconductive composite (i.e., the conductive elements are dispersedintegrally with or comprise the material comprising the planarizingsurface), such as a polymer matrix having conductive particles dispersedtherein or a conductive coated fabric, among others. The conductive pad610, the interposed pad 612, and the electrode 614 may be fabricatedinto a single, replaceable assembly. The processing pad assembly 604 isgenerally permeable or perforated to allow electrolyte to pass betweenthe electrode 614 and top surface 620 of the conductive pad 610. In theembodiment depicted in FIG. 6, the processing pad assembly 604 isperforated by apertures 622 to allow electrolyte to flow therethrough.In one embodiment, the conductive pad 610 is comprised of a conductivematerial disposed on a polymer matrix disposed on a conductive fiber,for example, tin particles in a polymer matrix disposed on a wovencopper coated polymer. The conductive pad 610 may also be utilized forthe contact assembly 250 in the embodiment of FIG. 3C.

A conductive foil 616 may additionally be disposed between theconductive pad 610 and the subpad 612. The foil 616 is coupled with apower source 242 and provides uniform distribution of voltage applied bythe source 242 across the conductive pad 610. In certain embodiments notincluding the conductive foil 616, the conductive pad 610 may be coupleddirectly, for example, via a terminal integral to the pad 610, to thepower source 242. Additionally, the pad assembly 604 may include aninterposed pad 618, which, along with the foil 616, provides mechanicalstrength to the overlying conductive pad 610. Examples of suitable padassemblies are described in the previously incorporated U.S. Patent No.6,991,528 and U.S. patent application Ser. No. 10/455,895.

The Electropolishing Cell

The electropolishing cell 700 provides an electrochemical polishing andpolishing cell configured to remove and/or deposit metal ontosemiconductor substrates. A polishing cell capable of electropolishingmay be used as the electropolishing cell 700. An example of such aprocessing cell is a SlimCell ECP™ processing chamber commerciallyavailable from Applied Materials, Inc., of Santa Clara, Calif. Thefollowing apparatus description is illustrative, and should not beconstrued or interpreted as limiting the scope of the invention.

One embodiment of the electropolishing cell 700 for the system describedherein uses a small volume cell, i.e., a cell weir volume that housesless than about 4 liters of electrolyte in the cell itself, preferablybetween about 1 and 3 liters, and potentially between about 2 and about8 liters of electrolyte solution in an adjacent fluidly connected supplytank. The electrochemical polishing cell 700 is generally configured tofluidly isolate a first electrode and a second electrode, for example,the substrate surface that is to be electropolished, from each other viaa cation membrane positioned between the substrate being processed andthe first and second electrodes of the polishing cell. Additionally, thepolishing cell of the invention is generally configured to provide afirst fluid solution to a first electrode compartment, i.e., the volumebetween the upper surface of the first electrode and the lower surfaceof the membrane, and a second fluid solution (a polishing solution) tothe second electrode compartment, i.e., the volume of fluid positionedabove the upper membrane surface. Alternatively, the same fluidsolution, polishing composition, may be supplied to the first and secondcompartments. Optionally, the first electrode of the polishing cellgenerally includes a plurality of slots formed therein, the plurality ofslots being positioned parallel to each other. A membrane support havinga plurality of slots or channels formed in a first side of the assembly,along with a plurality of bores formed into a second side of themembrane support, wherein the plurality of bores are in fluidcommunication with the slots on the opposing side of the membranesupport.

FIG. 7 illustrates a perspective and partial sectional view of anexemplary electrochemical polishing cell 700 of the invention. Polishingcell 700 generally includes an outer basin 701 and an inner basin 702positioned within outer basin 701. Inner basin 702 is generallyconfigured to contain a solution that is used to polish a metal, e.g.,copper, onto a substrate during an electrochemical polishing process.During the polishing process, the polishing solution is generallycontinuously supplied to inner basin 702 (at about 1 gallon per minutefor a 10 liter polishing cell, for example), and therefore, thepolishing solution continually overflows the uppermost point of innerbasin 702 and runs into outer basin 701. The overflow polishing solutionis then collected by outer basin 701 and drained therefrom forrecirculation into basin 702. Optionally, and illustrated in FIG. 7, thepolishing cell 700 may be positioned at a tilt angle, i.e., the frameportion 703 of polishing cell 700 is generally elevated on one side suchthat the components of polishing cell 700 are tilted between about 3°and about 30°. Therefore, in order to contain an adequate depth ofpolishing solution within inner basin 702 during plating operations, theuppermost portion of basin 702 may be extended upward on one side ofpolishing cell 700, such that the uppermost point of inner basin 702 isgenerally horizontal and allows for contiguous overflow of the polishingsolution supplied thereto around the perimeter of basin 702.

The frame member 703 of polishing cell 700 generally includes an annularbase member 704 secured to frame member 703. Since frame member 703 iselevated on one side, the upper surface of base member 704 is generallytilted from the horizontal at an angle that corresponds to the angle offrame member 703 relative to a horizontal position. Base member 704includes an annular or disk shaped recess formed therein, the annularrecess being configured to receive a disk shaped electrode member 705.Base member 704 further includes a plurality of fluid inlets/drains 709positioned on a lower surface thereof. Each of the fluid inlets/drains709 are generally configured to individually supply or drain a fluid toor from either the first electrode compartment or the second electrodecompartment of polishing cell 700.

In a polishing configuration, the electrode member 705 generallyincludes a plurality of slots 707 formed therethrough, wherein the slots707 are generally positioned in parallel orientation with each otheracross the surface of the electrode member 705. The parallel orientationallows for the electrolyte to flow downwardly across the first electrodesurface and into one of the slots 707. Polishing cell 700 furtherincludes a membrane support assembly 706. Membrane support assembly 706is generally secured at an outer periphery thereof to base member 704,and includes an interior region 708 configured to allow fluids to passtherethrough via a sequence of oppositely positioned slots and bores.The membrane support assembly may include an o-ring type seal positionednear a perimeter of the membrane, wherein the seal is configured toprevent fluids from traveling from one side of the membrane secured onthe membrane support 706 to the other side of the membrane.

FIG. 8 illustrates a perspective view of base member 704. The uppersurface of base member 704 generally includes an annular recess 801configured to receive a disk shaped electrode member 705 in the recessedportion. Further, the surface of annular recess 801 generally includes aplurality of channels 802 formed therein. Each of channels 802 aregenerally positioned in parallel orientation with each other andterminate at the periphery of recess region 801. Additionally, theperiphery of recessed region 801 also includes an annular drain channel803 that extends around the perimeter of recessed region 801. Each ofthe plurality of parallel positioned channels 802 terminate at opposingends into annular drain channel 803. Therefore, channels 802 may receivefluids from channels 802 and transmit the fluids to a drain channel 803via base channels 802. The vertical wall that defines recessed region801 generally includes a plurality of slots 804 formed into the wall.The slots 804 are generally positioned in parallel orientation with eachother, and further, are generally positioned in parallel orientationwith the plurality of channels 802 formed into the lower surface ofrecessed region 801. Base member 704 also includes at least one fluidsupply conduit 805 configured to dispense a fluid into the firstelectrode region of polishing cell 700, along with at least onepolishing solution supply conduit 806 that is configured to dispense apolishing solution into the an electrode compartment of polishing cell700. The respective supply conduits 805 and 806 are generally in fluidcommunication with at least one fluid inlet 709 positioned on a lowersurface of base member 704, as illustrated in FIG. 7. Base member 704generally includes a plurality of conduits formed therethrough (notshown), wherein the conduits are configured to direct fluids received byindividual fluid inlet 709 to the respective electrode chambers ofpolishing cell 700.

In one optional embodiment of the invention, FIG. 9 illustrates aperspective view of base member 704 having the disk shaped electrodemember 705 positioned therein. The electrode member 705, which isgenerally a disk shaped member, i.e., a insoluble-type generally used tosupport electrochemical polishing operations, generally includes aplurality of slots 902 formed therein. The slots 902 generally extendthrough the interior of the electrode member 705 and are in fluidcommunication with both the upper surface and the lower surface of theelectrode member 705. As such, slots 902 allow fluids to travel throughthe interior of the electrode member 705 from the upper surface to thelower surface. Slots 902 are positioned in parallel orientation witheach other. However, when the electrode member 705 is positioned withinannular recess 801 of base member 704, the parallel slots 902 of theelectrode member 705 are generally positioned orthogonal to both slots804 and channels 802 of base member 704, as illustrated in FIG. 9.Additionally, slots 902 generally do not continuously extend across theupper surface of the electrode member 705. Rather, slots 902 are brokeninto a longer segment 903 and a shorter segment 904, with a space 905between the two segments, which operates to generate a longer currentpath through anode 10 from one side to the other. Further, adjacentlypositioned slots 902 have the space 905 positioned on opposite sides ofthe first electrode member's upper surface. The current path from thelower side of first electrode member to the upper side of the firstelectrode member generally includes a back and forth type path betweenthe respective channels 902 through the spaces 905. Further, thepositioning of spaces 905 and channels 902 provides for improvedconcentrated Newtonian fluid removal from the surface of the electrodemember 705, as the positioning of channels 902 provides a shortestpossible distance of travel for the dense fluids to be received inchannels 902.

FIG. 10 illustrates an exploded perspective view of an exemplarymembrane support assembly 706 of the invention. Membrane supportassembly 706 generally includes an upper ring shaped support member1001, an intermediate membrane support member 1000, and a lower supportmember 1012. Upper and lower support member's 1001 and 1012 aregenerally configured to provide structural support to intermediatemembrane support member 1000, i.e., upper support member 1001 operatesto secure intermediate membrane support member 1000 to lower supportmember 1012, while lower support member 1012 receives intermediatemembrane support member 1000. Intermediate membrane support member 1000generally includes a substantially planar upper surface having aplurality of bores partially formed therethrough. A lower surface ofintermediate membrane support member 1000 generally includes a taperedouter portion 1003 and a substantially planar inner membrane engagingsurface 1006. An upper surface of lower support member 1012 may includea corresponding tapered portion configured to receive the taperedsection 1003 of intermediate membrane support member 1000 thereon. Themembrane engaging surface 1006 generally includes a plurality ofparallel positioned/orientated channels 1005. Each of the channels 1005formed into the lower surface of intermediate membrane support member1000 are in fluid communication with at least one of the plurality ofbores partially formed through the planar upper surface. The channels1005 operate to allow a membrane positioned in the membrane supportassembly to deform slightly upward or downward in the region of thechannels 1005, which provides a flow path for air bubbles and fluids totravel to the perimeter of the membrane and be evacuated from the firstelectrode chamber.

In operation, the polishing cell 700 of the invention provides a smallvolume (electrolyte volume) processing cell that may be used for copperelectrochemical polishing processes, for example. Polishing cell 700 maybe horizontally positioned or positioned in a tilted orientation, i.e.,where one side of the cell is elevated vertically higher than theopposing side of the cell, as illustrated in FIG. 7. If polishing cell700 is implemented in a tilted configuration, then a tilted headassembly and substrate support member may be utilized to immerse thesubstrate at a constant immersion angle, i.e., immerse the substratesuch that the angle between the substrate and the upper surface of theelectrolyte does not change during the immersion process. Further, theimmersion process may include a varying immersion velocity, i.e., anincreasing velocity as the substrate becomes immersed in the electrolytesolution. The combination of the constant immersion angle and thevarying immersion velocity operates to eliminate air bubbles on thesubstrate surface.

Assuming a tilted implementation is utilized, a substrate is firstimmersed into a polishing solution contained within inner basin 702.Once the substrate is immersed in the polishing solution, an electricalpolishing bias is applied between a conductive material layer on thesubstrate and the electrode member 705 positioned in a lower portion ofpolishing cell 700. The electrical plating bias generally operates tocause metal ions to dissolute from the anodic substrate surface. Thepolishing solution supplied to inner basin 702 is continually circulatedthrough inner basin 702 via fluid inlet/outlets 709. More particularly,the polishing solution may be introduced in polishing cell 700 via afluid inlet 709. The solution may travel across the lower surface ofbase member 704 and upward through one of fluid apertures 806. Thepolishing solution may then be introduced into the first electrodechamber via a channel formed into polishing cell 700 that communicateswith the first electrode chamber at a point above membrane support 706.Similarly, the polishing solution may be removed from the firstelectrode chamber via a fluid drain positioned above membrane support706, where the fluid drain is in fluid communication with one of fluiddrains 709 positioned on the lower surface of base member 704. Forexample, base member 704 may include first and second fluid apertures806 positioned on opposite sides of base member 404. The oppositelypositioned fluid apertures 806 may operate to individually introduce anddrain the polishing solution from the first electrode chamber in apredetermined direction, which also allows for directional flow control.The flow control direction provides control over removal of light fluidsat the lower membrane surface, removal of bubbles from the chamber, andassists in the removal fluids from the first electrode surface via thechannels 802 formed into base 704.

Once the polishing solution is introduced into the first electrodechamber, the polishing solution travels upward through diffusion plate710. Diffusion plate 710, which is generally a ceramic or other porousdisk shaped member, generally operates as a fluid flow restrictor toeven out the flow pattern across the surface of the substrate. Further,the diffusion plate 710 operates to resistively damp electricalvariations in the electrochemically active area the anode or cationmembrane surface. Additionally, embodiments of the invention contemplatethat the ceramic diffusion plate 710 may be replaced by a hydrophilicplastic member, i.e., a treated PE member, a PVDF member, a PP member,or other material that is known to be porous and provide theelectrically resistive damping characteristics provided by ceramics.However, the polishing solution introduced into the second electrodechamber is not permitted to travel downward through the membrane (notshown) positioned on the lower surface 1006 of membrane support assembly706 into the first electrode chamber, as the first electrode chamber isfluidly isolated from the second electrode chamber by the membrane. Thefirst electrode chamber includes separate individual fluid supply anddrain sources configured to supply a polishing solution to the firstelectrode chamber. The solution supplied to the first electrode chambercirculates exclusively through the first electrode chamber and does notdiffuse or otherwise travel into the second electrode chamber, as themembrane positioned on membrane support assembly 706 is not fluidpermeable in either direction.

Additionally, the flow of the fluid solution into the first electrodechamber is directionally controlled in order to maximize polishingparameters. For example, the polishing solution may be communicated tothe first electrode chamber via an individual fluid inlet 709. Fluidinlet 709 is in fluid communication with a fluid channel formed into alower portion of base member 704 and the fluid channel communicates thesubstrate surface to one of apertures 805. A seal positioned radiallyoutward of apertures 805, in conjunction with the surrounding structure,directs the polishing solution flowing out of apertures 805 upward andinto slots 804. Thereafter, the polishing solution generally travelsacross the upper surface of the electrode member 705 towards theopposing side of base member 704, which in a tilted configuration, isgenerally the higher side of polishing cell 700. The polishing solutiontravels across the surface of the first electrode below the membranepositioned immediately above. Once the polishing solution reaches theopposing side of the electrode member 705, it is received into acorresponding fluid channel 804 and drained from polishing cell 700 forrecirculation thereafter.

As discussed above, slots 902 are generally parallel to each other andare orthogonal to channels 804. Therefore, slots 902 are also orthogonalto channels 802 and formed into the lower surface of base member 704. Assuch, each of slots 902 or finally intersect several of channels 802.This configuration allows the polishing solution received within slots902 to be communicated to one or more of channels 802. Thereafter, thepolishing solution may be communicated via channels 802 to the annulardrain channel 803 positioned within recess 801. The drain 803 incommunication with channels 802 may generally be communicated throughbase plate 704 and back to a central supply tank, where the polishingsolution may be treated and resupplied to the cell.

The polishing solution may be removed from the first electrode chambervia an air vent/drain 1101, as illustrated in FIG. 11. Air vent/drain1101, which may include multiple ports, is generally positioned on theupper side of electrochemical polishing cell 700, and therefore, ispositioned to receive contaminants generated at the membrane surface.Air vents 1101 are generally in fluid communication with the polishingsolution tank discussed above, and therefore, communicates the dilutedpolishing solution received therein back to the polishing solution tank.Any bubbles trapped by air vent 1101 may also be removed from the secondelectrode chamber vented to atmosphere or simply maintained within thepolishing solution tank and not recirculated into the anode chamber.

System Operation

Substrates 122 may be polished in one embodiment using the systems 100,200 described herein. The substrate 122 may comprise feature definitionsformed in a dielectric material, a barrier layer deposited conformallyover the dielectric layer and in the feature definitions, and aconductive layer disposed on the barrier to fill feature definitions.The conductive layer may be tungsten, copper, a layer having bothexposed tungsten and copper, and the like. The barrier layer may beruthenium, tantalum, tantalum nitride, titanium, titanium nitride andthe like and the dielectric layer includes one or more dielectric layersincluding oxides, carbon doped silicon oxides, silicon carbide, siliconcarbide derivatives including nitrogen/and/oxygen doped silicon carbide,and amorphous carbon as examples.

The polishing methods described herein may also be practiced on otherelectroprocessing systems. The polishing methods may comprise a computerreadable media and may be stored in the memory 112 of the controller108, typically as a software routine. The software routine may also bestored and/or executed by a second CPU (not shown) that is remotelylocated from the hardware being controlled by the CPU 110.

Although the process of the present invention is discussed as beingimplemented as a software routine, some of the method steps that aredisclosed therein may be performed in hardware as well as by thesoftware controller. As such, the invention may be implemented insoftware as executed upon a computer system, in hardware as anapplication specific integrated circuit or other type of hardwareimplementation, or a combination of software and hardware.

In one embodiment of the process, a substrate 122 is introduced into thesystem and transferred to an electropolishing cell 700. The conductivematerial, for example, tungsten, which may be deposited to a thicknessof 15,000 Å above the level of the dielectric layer is removed in afirst polishing step to a pre-determined level in the electropolishingcell 700. In one example, the first portion of the conductive material,the bulk portion, is removed by an electropolishing process to leave aresidual amount or thickness of conductive material, for example, athickness of about 500 Å. The amount of material to be removed is basedon the embodiment of the polishing process to be performed in the systemand the selected material to be polished. Alternatively, the conductivematerial may be removed to the extent the conductive material isdiscontinuous over the surface of the substrate. Such discontinuousconductive material may also be referred to as residual material.

The substrate 122 may then be transferred to the planarizing module 106,196 for subsequent polishing. In one embodiment of the polishing processfollowing the electropolishing cell process, the conductive material ofthe substrate may be removed by a chemical mechanical polishing processthat may be performed on one or more stations. For example, the residualconductive material may be polished in a CMP apparatus at station 128,then polished to remove any remaining conductive material on a CMPapparatus at station 130, followed by a CMP or Ecmp barrier removalprocess at station 132.

In another embodiment of the polishing process following theelectropolishing cell process, the conductive material of the substratemay be removed by an electrochemical mechanical polishing process thatmay be performed on one or more stations. For example, the residualconductive material may be polished first in an Ecmp apparatus atstation 128, then polished to remove any remaining conductive materialon an Ecmp apparatus at station 130, followed by a CMP or Ecmp barrierremoval process at station 132. The Ecmp apparatus may include the Ecmpapparatus described herein with regard to FIGS. 2-6.

In a further embodiment of the polishing process following theelectropolishing cell process, the conductive material of the substratemay be removed by chemical mechanical polishing, electrochemicalchemical mechanical polishing, or both, that may be performed on one ormore stations. For example, the residual conductive material may bepolished first in an Ecmp apparatus at station 128, then polished toremove any remaining conductive material on an Ecmp or CMP apparatus atstation 130, followed by a CMP or Ecmp barrier removal process atstation 132. In another example, the residual material may be removedwith a CMP process performed at a first station 128 followed by an Ecmpprocess on the same station using an apparatus adapted to perform bothtypes of processes. The remaining barrier material may then be removedat a second station. In such an example, a portion of the barrier layermay be removed at the first station. In another example, the residualmaterial and a portion of the barrier material may be removed with a CMPor Ecmp process at a first station 128 followed by removing theremaining barrier material with an Ecmp or CMP process at a secondstation, such as station 132. In another example, any residualconductive material following the electropolishing cell process may beremoved at either station 128 or 132 by a chemical mechanical polishingprocess or an electrochemical mechanical process followed by removingthe remaining barrier material at another station, such as station 132.

An Ecmp process may be performed as follows at one of the Ecmp stations128, 130. The substrate 122 is transferred from the electropolishingcell 700 to the planarizing module 106 and the substrate 122 retained inthe planarizing head 204 over the processing pad assembly 222 disposedin, for example, the first Ecmp station 128. Although the pad assemblyof FIGS. 2, 3A, 4A-C and 5, is utilized in one embodiment it iscontemplated that pad and contact assemblies as described in FIGS. 3B-Cmay alternatively be utilized. The planarizing head 204 is loweredtoward the platen assembly 222 to place the substrate 122 in contactwith the top surface of the pad assembly 222. The substrate 122 is urgedagainst the pad assembly 222 with a force of less than about 1.5 poundsper square inch (psi), for example, between about 0.1 psi and about 1psi. In one embodiment, the force is about 0.3 psi. Relative motionbetween the substrate 122 and processing pad assembly 222 is provided.In one embodiment, the planarizing head 204 is rotated between about 30and about 60 revolutions per minute, while the pad assembly 222 isrotated between about 7 and about 35 revolutions per minute.

The polishing solution is an electrolyte that is supplied to theprocessing pad assembly 604 to establish a conductive path therethroughbetween the substrate 122 and the electrode 614. An example of atungsten polishing solution is further described in U.S. patentapplication Ser. No. 10/948,958, entitled METHOD AND COMPOSITION FORPOLISHING A SUBSTRATE, filed on Sep. 24, 2004, published as U.S.2006/0021974, which is incorporated by reference to the extent notinconsistent with the disclosure and claims aspects herein. The powersource 242 provides a bias voltage between the top surface of the padassembly 222 and the electrode 292. One or more of the contact elements250 of the pad assembly 222 are in contact with the substrate 122 andallows the voltage to be coupled thereto. Electrolyte filling theapertures 210 between the electrode 292 and the substrate 122 provides aconductive path between the power source 242 and substrate 122 to drivean electrochemical mechanical planarizing process that results in theremoval of the tungsten material, or other conductive film disposed onthe substrate, by an anodic dissolution method. The process generallyhas a tungsten removal rate of about 4000 Å/min.

An endpoint of the Ecmp process is determined. The endpoint may bedetermined using a first metric of processing provided by the meter 244.The meter 244 may provide charge, voltage or current informationutilized to determine the remaining thickness of the conductive material(e.g., the tungsten or copper layer) on the substrate. In anotherembodiment, optical techniques, such as an interferometer utilizing thesensor 254, may be utilized. The remaining thickness may be directlymeasured or calculated by subtracting the amount of material removedfrom a predetermined starting film thickness. In one embodiment, theendpoint is determined by comparing the charge removed from thesubstrate to a target charge amount for a predetermined area of thesubstrate. Examples of endpoint techniques that may be utilized aredescribed in U.S. patent application Ser. No. 10/949,160, filed Sep. 24,2004, published as U.S. 2005/0061674, and U.S. Pat. No. 6,837,983,issued Jan. 4, 2005, and U.S. Pat. No. 7,112,270, issued Sep. 26, 2006,all of which are hereby incorporated by reference in their entireties.

One example of a substrate handling process comprises introducing asubstrate 122 into a wafer cassette 118 disposed on the factoryinterface 102. The substrate is then retrieved by the interface robot120 and in one embodiment transferred to an electropolishing cell 190A,190B, or 190C disposed on the factory interface 102. Followingelectropolishing in the cell 190A, 190B, or 190C, the substrate iscleaned in the cleaner module 116. Alternatively, the substrate may becleaned in the cleaner module prior to introduction into the cell 190A,190B, or 190C.

The substrate 122 is then transferred to the planarizing module 106 viathe input robot 104. In the planarizing module 106, the substrate 122,the polishing head 148 may retrieve the substrate 122 from a load cup142 and transfer the substrate to the first station 128 for processingas described herein. The substrate 122 may then be transferred andprocessed on one or more additional stations as necessary. In analternative embodiment, the electropolishing cell 190D is positioned onthe planarizing module 106, the substrate is then transferred to theelectropolishing cell 190D prior to polishing at one of the stations128, 130, and 132 described herein. After processing, the substrate canbe removed from the planarizing module 106, transferred to the cleanermodule 116, and then returned to the cassettes 118 for retrieval fromthe system 100.

While the foregoing is directed to embodiments of the invention, otherand further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

1. A polishing apparatus, comprising: a planarizing module; at least oneelectrochemical mechanical polishing station disposed on the planarizingmodule; at least one polishing head disposed above the planarizingmodule, wherein the at least one polishing head is adapted toselectively lower a substrate retained in the polishing head to theelectrochemical mechanical polishing station; a factory interfacedisposed adjacent the planarizing module; a loading robot disposedadjacent both the factory interface and the planarizing module; and anelectrochemical polishing station.
 2. The apparatus of claim 1, whereinthe factory interface comprises: a cleaning module; an input moduledisposed adjacent the cleaning module; an interface robot disposedadjacent the cleaning module and the input module; and one or more wafercassettes disposed adjacent the interface robot.
 3. The apparatus ofclaim 2, wherein the electrochemical polishing station is disposedadjacent the cleaning module.
 4. The apparatus of claim 2, wherein theelectrochemical polishing station is disposed in the cleaning module. 5.The apparatus of claim 2, wherein the electrochemical polishing stationis disposed adjacent the input module.
 6. The apparatus of claim 1,wherein the at least one electrochemical mechanical polishing stationscomprises: at least one pad support; a conductive polishing pad retainedby the pad support; an electrode disposed between the conductivepolishing pad and the pad support; and an electrolyte delivery systemadapted to provide electrolyte to a processing surface of the conductivepolishing pad.
 7. The apparatus of claim 1, wherein the electrochemicalpolishing station comprises: a cell body configured to contain apolishing solution; a first electrode positioned in the cell body,wherein the first electrode is configured to anodically bias asubstrate; and a second electrode positioned in the cell body, whereinthe second electrode is configured to function as a cathode.
 8. Theapparatus of claim 7, wherein the electrochemical polishing station isconfigured to remove conductive material from a substrate in amechanical free polishing process.
 9. A polishing apparatus, comprising:a planarizing module; three electrochemical mechanical polishingstations disposed on the planarizing module; four polishing headsdisposed above the planarizing module, wherein each of the polishingheads is adapted to selectively lower a substrate retained in thepolishing head to the electrochemical mechanical polishing station; afactory interface disposed adjacent the planarizing module; a loadingrobot disposed adjacent both the factory interface and the planarizingmodule; and an electrochemical polishing station disposed on theplanarizing module.
 10. The apparatus of claim 9, wherein theplanarizing module further comprises a load cup disposed adjacent atleast one of the electrochemical mechanical polishing stations.
 11. Theapparatus of claim 10, wherein the electrochemical polishing station isdisposed between the load cup and at least one of the electrochemicalmechanical polishing stations.
 12. The apparatus of claim 9, wherein theelectrochemical polishing station is disposed between two of theelectrochemical mechanical polishing stations.
 13. The apparatus ofclaim 10, wherein the electrochemical mechanical polishing stationscomprise: at least one pad support; a conductive polishing pad retainedby the pad support; an electrode disposed between the conductivepolishing pad and the pad support; and an electrolyte delivery systemadapted to provide electrolyte to a processing surface of the conductivepolishing pad.
 14. The apparatus of claim 10, wherein theelectrochemical polishing station comprises: a cell body configured tocontain a polishing solution; a first electrode positioned in the cellbody, wherein the first electrode is configured to anodically bias asubstrate; a second electrode positioned in the cell body, wherein thesecond electrode is configured to function as a cathode; and a polishingsolution delivery system adapted to provide electrolyte to the cellbody.
 15. The polishing apparatus of claim 14, wherein theelectrochemical polishing station is configured to remove conductivematerial from a substrate in a mechanical free polishing process by theapplication of a bias in the presence of a conductive polishing solutionto remove conductive material by anodic dissolution.
 16. A method ofpolishing a substrate comprising feature definitions formed in adielectric material, a barrier layer deposited conformally over thedielectric layer and in the feature definitions, and a conductive layerdisposed on the barrier layer to fill the feature definitions,comprising: providing a system comprising a factory interface, anelectrochemical polishing station, and a planarizing module containingthree electrochemical mechanical polishing stations; introducing asubstrate to the electrochemical polishing station configured to removeconductive material from a substrate in a mechanical free polishingprocess by the application of a bias in the presence of a conductivepolishing solution to remove conductive material by anodic dissolution;removing a bulk portion of the conductive layer from the substrate;transferring the substrate to the first electrochemical mechanicalpolishing station; polishing the substrate to remove a residual portionof the conductive layer of the substrate; transferring the substrate tothe second electrochemical mechanical polishing station; removing anyremaining conductive material from the surface of the substrate toexpose the barrier layer; transferring the substrate to the thirdelectrochemical mechanical polishing station; and removing the barrierlayer from the substrate.
 17. The method of claim 16, whereintransferring the substrate from the electrochemical polishing stationcomprises retrieving the substrate from a load cup and transferring thesubstrate to the first electrochemical mechanical processing station.18. The method of claim 16, wherein polishing the substrate to remove aresidual portion of the conductive layer from the substrate comprises:contacting the substrate with a pad assembly; and providing relativemotion between the pad assembly and the substrate.
 19. The method ofclaim 16, wherein the electrochemical polishing station is located inthe planarizing module.
 20. The method of claim 16, wherein theelectrochemical polishing station is located adjacent to and between thefactory interface and the planarizing module.